For UK and European patent applications, an Examiner will raise an “added subject matter” objection if they believe the application has been amended to add any information which extends beyond the information included in the application when it was originally filed.
European law requires that amendments be “directly and unambiguously derivable” from the application as filed. Similarly, UK law requires that a granted patent does not extend beyond that disclosed in the application.
An amendment does not have to be taken word-for-word from the application as filed. However, as an example, an objection of added subject matter may result from an amendment claiming a group of features if those features are only disclosed separately in the application, and not as a group. Added subject matter may also result if terminology is changed in an application without there being basis for the new wording in the original text.
Added subject matter may also arise from the omission or deletion of features. For example if an application describes features A, B and C as a combination, a claim directed to a combination of A and B, without requiring C, might result in an added subject matter objection.
Are there differing considerations pre- and post-grant?
During examination of a UK or European patent application, the Applicant will have an opportunity to amend the claims when the Examiner raises an added subject matter objection.
If an objection of added subject matter is raised after grant, for example in Opposition proceedings against a European patent, it may be more difficult to overcome the objection. This is because it is not permitted to broaden the scope of the claims of the patent after grant. This restriction may prevent any added subject matter from being deleted, and so may result in revocation of the patent. For this reason, it is crucial to consider the risk of adding subject matter when making amendments during prosecution of a patent application.